Previously only 4 MHz and 8 MHz were allowed. Given the tolerance
allowed in the WS2812 timing spec, frequency ranges around those
two can be used too which is useful for boards in which it is
difficult to generate those specific frequencies.
The WS2812 is very common in LED strips as it is an integrated
controller and LED. It is driven by a single data line, but
the timing requirements can be met by using most SPI controllers
and the use of DMA.
This driver has been validated on the nRF52 arch both with a
single LED and a strip of 144.
Signed-off-by: Brennan Ashton <bashton@brennanashton.com>
